Expression of glucocorticoid receptor α- and β-isoforms in human cells and tissues

Abstract

Alternative splicing of the human glucocorticoid receptor (GR) primary transcript generates two protein isoforms: GR-α and GR-β. We investigated the expression of both GR isoforms in healthy human cells and tissues. GR-α mRNA abundance (×106 cDNA copies/μg total RNA) was as follows: brain (3.83 ± 0.80) > skeletal muscle > macrophages > lung > kidney > liver > heart > eosinophils > peripheral blood mononuclear cells (PBMCs) > nasal mucosa > neutrophils > colon (0.33 ± 0.04). GR-β mRNA was much less expressed than GR-α mRNA. Its abundance (×103 cDNA copies/μg total RNA) was as follows: eosinophils (1.55 ± 0.58) > PBMCs > liver ≥ skeletal muscle > kidney > macrophages > lung > neutrophils > brain ≥ nasal mucosa > heart (0.15 ± 0.08). GR-β mRNA was not found in colon. While GR-α protein was detected in all cells and tissues, GR-β was not detected in any specimen. Our results suggest that, in physiological conditions, the default splicing pathway is the one leading to GR-α. The alternative splicing event leading to GR-β is minimally activated.